People with chronic obstructive pulmonary disease (COPD) experience decreased strength and endurance of the skeletal muscles which contributes to premature disability. Pulmonary rehabilitation, in particular aerobic exercise training, is a recognized approach for improving functional capacity and lessening distressing symptoms. But people with severe to very severe disease often have difficulty achieving higher intensities of aerobic exercise training. Resistance training can improve muscular strength so people use a smaller fraction of their total strength with aerobic training. This could enable these people to train at a higher aerobic intensity with less perceived effort. This study proposes a novel approach to pulmonary rehabilitation. Rather than concurrently train people with both aerobic and resistance exercise which is typical clinical practice, a sequential approach will be employed whereby COPD subjects will receive 8 weeks of resistance training focused on the lower body, followed by 8 weeks of aerobic exercise training. The study examines whether lower body resistance training prior to aerobic training is associated with greater gains in functional status than aerobic training alone or concurrent aerobic plus resistance training. In this experimental study 138 people with severe/very severe COPD will be randomized to 1 of 3 nurse-managed training groups: 1. a sequential training group comprised of 8 weeks of resistance training followed by 8 weeks of aerobic exercise training {S-RAT, resistance and aerobic training conducted sequentially), 2. a control group comprised of 8 weeks of 'sham'training followed by 8 weeks of concurrent aerobic training plus resistance training (Control-C-RAT, resistance and aerobic training conducted concurrently), and 3. a control group comprised of 8 weeks of 'sham'training followed by 8 weeks of aerobic training (Control-AT, aerobic training alone). The Control-C-RAT group controls for the total dose of exercise training (aerobic training plus resistance training) and provides the usual approach to pulmonary rehabilitation, e.g. concurrent employment of training modalities. The Control-AT group controls for the amount of contact with research staff and provides the 'standard of care', e.g. aerobic training. The following dependent variables will be assessed at study entry, after week 8, and after week 16: 1. aerobic exercise performance, 2. peripheral muscle mass, strength, endurance, 3. symptoms of breathlessness and fatigue, 4. functional status. This program employs a novel approach to pulmonary rehabilitation: lower body resistance training prior to initiating aerobic exercise training in order to maximize improvements in exercise tolerance, symptoms, and functional performance of physical activities. This knowledge will be used by clinicians in designing pulmonary rehabilitation programs for people with COPD, especially more severely disabled people.